1. Field of the Invention
This invention relates to tamper indicating closures for application to container necks. The tamper indicating feature indicates that the closure has been previously removed or an attempt has been made to remove it from the container. More particularly, this invention relates to a tamper indicating closure in which a tamper indicating band depends from the bottom of the cap skirt by spaced frangible webs. The band has a stop which coacts with a stop on the container neck so that as the closure cap is being unthreaded from the container neck the tamper indicating band is restrained against axial or rotational movement causing fracture of the frangible webs and separation of the band from the cap.
2. Description of the Related Art
At the present time, one of the most commonly used stop device for restraining the movement of the tamper indicating band on the container neck relative to the cap has been the provision of an inwardly directed bead on the tamper indicating band which coacts with an outwardly directed flange on the container neck. In the process of threading the cap onto the container neck the bead on the tamper indicating band snaps over the flange on the container neck. In the unthreading process the bead is restrained against axial motion by the container flange so that the frangible webs between the bottom of the cap skirt and the top of the tamper indicating band are fractured primarily in tension. There are many shortcomings with this type of tamper indicating band restraint. Among these are skewing of the band so that not all of the tamper indicating webs are broken during the unthreading process. This type of difficulty can be obviated by changing the stops to cooperating ratchet teeth on the tamper indicating band and container neck. In the unthreading direction, radial stop surfaces on the band ratchet teeth abut radial stop surfaces on the container neck ratchet teeth. The frangible webs are thus caused to fracture primarily in shear since the band does not rotate with the cap.
In many instances it is desirable to remove the severed tamper indicating band with the cap rather than have the band remain on the container neck. For example in the case of reusable bottles, it is desirable to remove the tamper indicating band from the container neck so that it will not require additional processing steps in the bottling operation. Likewise, when the closure is applied to a plastic quart oil container, it is desirable to remove the band with the cap to eliminate the possibility of the band sliding off the container neck and into the engine crank case when the container is inverted to allow oil to flow from the container. In the past the retention of the tamper indicating band with the cap has been accomplished with closures of the snap over bead/flange design. When cooperating ratchet teeth have been used, the band has either been left on the container neck or it has been removed separately as a tear strip before there is any attempt to unthread the cap from the container neck.